Thinly provisioned storage systems provide the appearance of having more storage capacity than is actually available. A thinly provisioned storage system is commonly used when actual physical storage capacity is shared among multiple entities, such as people or groups of people, and when the actual physical storage used by those entities is substantially less than an amount provisioned for use by those entities.
In a thinly provisioned storage system, actual physical storage typically is allocated and used when data is written to the storage system. As storage usage increases, actual physical storage can be added into the storage system with little overhead or impact on the rest of the system.
One problem with thinly provisioned storage systems is the risk of data loss, and related outcomes due to data loss. Data loss can occur when operations that write data fail because actual physical storage is not available. Such data loss also can result in a poor user experience because allocation operations may be successful (due to thin provisioning) whereas write operations to successfully allocated storage can fail due to a lack of actual physical storage capacity.